Motor vehicle wiper comprising a wear indicator

ABSTRACT

A motor vehicle wiper includes a wiper blade mounted on the free end of a wiper arm and pressing a wiping stem against the glass to be wiped. The wiper is provided with a wear indicator using a substance based at least on an azo compound.

BACKGROUND

This invention concerns the wiping means of the windows of motorvehicles and, more specifically, their wear.

A wiper blade equipped with its elastic wiper stem is a piece of thevehicle that wears out and which must be replaced regularly if one wantsto guarantee a good wiping quality of the window. This proves to be evenmore important for the driving safety while one is using the wiper bladeon the front windshield of the vehicle.

The sources of wear are numerous and the blade is susceptible todegrading as much at the level of the wiper stem as at the joints andthe articulation mount that carries it.

For example, the wiper stem is susceptible to wear via friction but canalso wear due to the deterioration of the material that it is made of.

The agents of such deterioration are principally:

sun light, and more specifically, ultraviolet rays that light contains;

oxygen because, even if the vehicle is normally parked in a closedgarage, and thus sheltered from sunlight, it cannot be sheltered fromoxidation;

temperature, variations of temperature, and humidity;

ozone and all electromagnetic radiation from the environment.

Thus, it appears to be pertinent to determine the lifespan of the wiperblade as a function of its time exposed to the air.

In addition, frequently drivers are incapable of remembering when theylast changed their wiper blades. In effect, such an operation is notgenerally entrusted to a vehicle repair specialist who can, for example,proceed to a systematic, regular replacement of the blades.

It is known, for example, from application WO/01896, to use wearindicators that change color as a result of exposure to the environment.This type of indicator presents the major inconvenience of only beingsensitive to one parameter of wear, for example ultraviolet rays.

The goal of this invention is to allow the driver to determine the stateof reliable wear of the wiper blades of his vehicle via a wear indicatorthat is representative of real wear constraints, and not dependent onsun exposure, that is to say the geographic or meteorological situation,or environment, for example pollution or altitude.

In order to achieve this goal, the invention proposes taking intoaccount, in the composition of the wear indicator, the principal agentsor parameters of the wear of the wiper stem of the wiper blades andtheir combined action in use conditions.

More precisely, the goal of the invention is a motor vehicle wipercomprising a wiper blade that is mounted on the free end of a wiper stemand pressing a wiper stem against a window to be wiper, in which thewiper is provided with an indicator comprising a substance based atleast on an azo compound.

It has been remarked that the sensitivity of the azo compounds tochemical (oxygen, ozone) and physical conditions (radiation,temperature, humidity) as well as to mechanical constraints iscomparable to that of the elastamers making up the wiping stem.

According to other characteristics of the invention;

the wear indicator is a multi-layered label comprising an adhesive layerand a plastic support film from at least one inert layer of a referencecolor and a reactive degradable layer, made up of a substance of adifferent color based on the azo compound;

the inert and reactive layers are formed via ink in which an inertchemical pigmentation, defining a reference color, and a base organicpigmentation from the azo by-products are respectively created;

the inks are successively placed on the plastic support viasilk-screening;

the plastic support is in polyvinyl, polypropylene, or polyester and iscovered with a protective layer fixed to the support film, in adetachable manner, via a semi-porous adhesive, this layer being pulledback during the mounting of the blade on the vehicle.

the wear indicator is carried by the wiper blade.

Other characteristics and advantages of the invention will becomeclearer in the reading of the detailed description that follows of oneexample of production, in reference to the attached drawings thatrepresent, respectively:

FIG. 1, front view of a example of an wear indicator of a wiperaccording to the invention;

FIG. 2, cut view according to the plane II—II of the wear indicatoraccording to FIG. 1.

One has represented on FIGS. 1 a motor vehicle wiper 10 that essentiallycomprises a wiper arm 12 at the free end 14 of which is mounted inarticulation a wiper blade 16.

The wiper blade 16 comprises an articulated structure 18 which carries,via claws 20, a wiping stem 22 generally created in a supple elastomermaterial. The articulated structure 18 is designed to press, with itsentire length, the wiping stem 22 against a window to be wiped on thecar,

Conforming to the specifications of the invention, the wiper blade 16carries an wear indicator 1 incorporating organic ink pigmented based onan azo by-product, sensitive and degradable as a result of the chemicalattacks and the mechanical constraints to which it is subjected.

The wear indicator 1 can also be attached to places other than thewiper, as long as it is easily visible while the wiper blade 16 ismounted on the vehicle.

One uses as azo by-product an alkaline-terrine salt azo with a sulfuricfunction. In other examples of production, the compounds used can bedouble-azos, tetra-double-azos, or sulfuric function azos, takenindividually or in combination. Preferably, the compound used furnishesa black color in such a way as to clearly distinguish the deep vibrantcolor that appears while the ink pigmented via the azo by-product isdecomposed.

In the production example, the wear indicator is created in the form ofa sticker label covered with a protective film 2 in polyethylene,resistant specifically to ultraviolet radiation and the oxygen in theair. This film adheres to the rest of the label via an adhesivesemi-porous layer, in order to be easily detached during installation ofthe blade 16.

It appears more precisely on FIG. 2, which illustrates the label 1 incut view, which figure makes up, in addition to the film 2, a supportfilm 3 in polyvinyl, the lower face of which is coated with an adhesive4 with a strong adhesion capability which allows the assurance ofdefinitive, reliable fixation of the wear indicator 1 on the blade 16.Other plastic materials can be used for the support film, for examplefrom polyester or polypropylene.

On the support film 3 is places a first layer of ink 5, colored yellowwith chemically inert pigments, and covered with a second layer of ink 6of which the color is obtained via incorporation of organic pigments ofazo by-products. At the fabrication of the wear indicator 1, the inklayers 5 and 6 are successively placed via a silk-screening technique.

The label is covered by a mask in the shape of a protective film 2,fixed to the support film 3 via a semi-porous adhesive 7. The mask ispulled back during the mounting of the blade on the vehicle whileremoving it from the support.

Over the course of time, chemical, physical, and mechanical attacksdestroy the azo pigments of the upper layer 6. Once totally decomposed,it then displays the yellow lower layer, which hasn't been subjected toany attacks and which indicates an advanced state of wear of the wipingstem.

One has the advantage to choose an intense coloration for the lowerlayer 5 while it is under the form of a lower degree of oxidation. Thus,noticing the changing color of the wear indicator will be clearer.

The invention is not limited to the example of production described andrepresented. For example, in order to better control the kinetic of thedegradation reaction, one can superimpose on the reactive layer adiffused layer that slows the contact between this layer and thechemical attacks. In addition, it is possible to mix the organicpigments to the mineral oxides, notably to some titanium oxide, in orderto improve the sensitivity of the indicator.

What is claimed is:
 1. A motor vehicle wiper including a wiper blademounted at the free end of a wiper arm in order to press a wiping stemagainst a window to be wiped, characterized by the wiper being providedwith an wear indicator comprising a substance based at least on an azocompound covered with a protective mask, wherein the wear indicator isactivated with the at least partial removal of the protective mask fromthe substance.
 2. The wiper according to claim 1, characterized by thewear indicator having multi-layers comprising an adhesive layer and aplastic support film of at least one inert layer made of a substance ofa reference color and a reactive degradable layer made from a substanceof a different color based on azo compounds.
 3. The wiper according toclaim 2, characterized by the inert and reactive layers being formedrespectively by an ink in which a chemically inert pigmentation,defining the reference color, and an organic pigment based on azoby-products are produced.
 4. The wiper according to claim 3,characterized by the organic pigments being mixed with mineral oxides.5. The wiper according to claim 3, characterized by the inks beingsuccessively placed on the plastic support via silk screening.
 6. Thewiper according to claim 2, characterized by the plastic support filmbeing of one of polyvinyl, polypropylene and polyester and being coveredby a the protective mask fixed to the support film in a detachablemanner, via a semi-porous adhesive, the mask being pulled back duringthe mounting of the blade on the wiper.
 7. The wiper according to claim1, characterized by the wear indicator being carried by the wiper blade.8. A motor vehicle wiper blade comprising: a wear indicator on the wiperincluding a substance based at least on an azo compound covered with aprotective mask, wherein the wear indicator is activated with at leastpartial removal of the protective mask from the substance.
 9. The wiperblade of claim 8 further comprising: the wear indicator havingmulti-layers including an adhesive layer and a plastic support film ofat least one inert layer made of a substance of a reference color and areactive degradable layer made from a substance of a different colorbased on azo compounds.
 10. The wiper blade of claim 9 furthercomprising: the inert and reactive layers being formed respectively byan ink in which a chemically inert pigmentation, defining the referencecolor, and an organic pigment based on azo by-products are produced. 11.The wiper blade of claim 10 further comprising: the organic pigmentsbeing mixed with mineral oxides.
 12. The wiper blade of claim 10 furthercomprising: the inks being successively placed on the plastic supportvia silk screening.
 13. The wiper blade of claim 9 further comprising:the plastic support film being of one of polyvinyl, polypropylene andpolyester and being covered by the protective mask fixed to the supportfilm in a detachable manner, via a semi-porous adhesive, the mask beingpulled back during the mounting of the blade on the wiper.
 14. A motorvehicle wiper comprising: a wiper blade mountable at a free end of awiper arm in order to press a wiping stem against a window to be wiped;and a wear indicator carried on the wiper blade including a substancebased at least on an azo compound covered with a protective mask,wherein the wear indicator is activated with the at least partialremoval of the protective mask from the substance, the wear indicatorhaving multi-layers including an adhesive layer and a plastic supportfilm of at least one inert layer made of a substance of a referencecolor and a reactive degradable layer made from a substance of adifferent color based on azo compounds, the inert and reactive layersbeing formed respectively by an ink in which a chemically inertpigmentation, defining the reference color, and an organic pigment basedon azo by-products are produced, the organic pigments being mixed withmineral oxides, the inks being successively placed on the plasticsupport via silk screening, the plastic support film being of one ofpolyvinyl, polypropylene and polyester and being covered by theprotective mask fixed to the support film in a detachable manner, via asemi-porous adhesive, the mask being pulled back during the mounting ofthe blade on the wiper.
 15. A wiper blade of a motor vehicle comprising:a wiper stem made of elastomers; and a wear indicator, wherein the wearindicator includes a substance based at least on an azo compound, thesubstance based on the azo compound having a sensitivity to chemical andphysical conditions and having mechanical constraints comparable to thatof the elastomers making up the wiper stem.
 16. The wiper blade of claim15 further comprising: the wear indicator having multi-layers includingan adhesive layer and a plastic support film of at least one inert layermade of a substance of a reference color and a reactive degradable layermade from a substance of a different color based on azo compounds. 17.The wiper blade of claim 16 further comprising: the inert and reactivelayers being formed respectively by an ink in which a chemically inertpigmentation, defining the reference color, and an organic pigment basedon azo by-products are produced.
 18. The wiper blade of claim 17 furthercomprising: the organic pigments being mixed with mineral oxides. 19.The wiper blade of claim 16 further comprising: the inks beingsuccessively placed on the plastic support via silk screening.
 20. Thewiper blade of claim 16 further comprising: the plastic support filmbeing of one of polyvinyl, polypropylene and polyester and being coveredby the protective mask fixed to the support film in a detachable manner,via a semi-porous adhesive, the mask being pulled back during themounting of the blade on the wiper.